Hello again!
Since we have the steps pretty well fleshed out, I figured it was about time to update the porting docs to describe how to add support for static-pie. Here is a patch with some notes about the steps I usually take when updating another architecture to support it.
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From afaa287e28e8e120bf55a7de368253f445a6deea Mon Sep 17 00:00:00 2001
From: linted <linted@users.noreply.github.com>
Date: Mon, 26 Sep 2022 13:40:50 -0400
Subject: [PATCH] Added some documentation on how to add static-pie support to
the porting guide
Signed-off-by: linted <linted@users.noreply.github.com>
---
docs/porting.txt | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/docs/porting.txt b/docs/porting.txt
index 380645801..31c188ae1 100644
--- a/docs/porting.txt
+++ b/docs/porting.txt
@@ -12,6 +12,8 @@ you are hacking on.
the shared library loader work requires you first have basic architecture
support working. Thus you should add ARCH_HAS_NO_SHARED and
ARCH_HAS_NO_LDSO to Config.ARCH's TARGET_ARCH
+- When static pie support is added this TARGET_arch can be appended to the
+ list in extra/Configs/Config.in
====================
=== libc sysdeps ===
@@ -56,6 +58,15 @@ you are hacking on.
usually these are written in assembler, but you may be able to cheat and
write them in C ... see other ports for more information
+- Once static and pie executables are stable, static-pie support can be
+ added by modifying crt1.S to calculate the address that the kernel loaded
+ the main elf. Once the elf load address is found, call reloc_static_pie to
+ perform all the dynamic relocations normally handled by ldso. This new
+ code should be placed at the begining of _start and surrounded by defines
+ so that it is only compiled into rcrt1.o and not the static or shared
+ versions. This is usually done by using the special L_rcrt1 preprocessor
+ define. i386 and x86_64 have good reference implementations.
+
====================
=== ldso sysdeps ===
====================
--
2.34.1